Purple heart originates in Mexico, where it spreads as a ground cover across warm, dry ground, and its tolerance of salt, drought, humidity, and poor soil reflects those origins precisely. The specific epithet pallida, meaning "pale," reads as a gentle irony: every part of this plant is boldly, insistently purple. The lance-shaped leaves are covered in pale hairs and the trailing stems can reach a foot tall, making it effective as a low ground cover, a slope planting, or a cascading container subject.

In midsummer, small pink flowers with bright yellow stamens appear at the stem ends, each lasting one day before closing. Full sun gives the deepest, richest purple color; shade shifts the foliage toward greenish-purple and dulls the effect considerably. In zones 10 to 11 it grows as a perennial; north of that it is treated as an annual or brought indoors for winter. Stem cuttings root quickly and are the standard way to propagate it. Pinching back encourages a denser, bushier habit rather than the long trailing stems that can become untidy if left to their own devices.